UPD784020 Datasheet, PDF (40/90 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCOMPUTER

mPD784020, 784021
8.8.2 Synchronous Serial Interface (CSI)
With this interface, the master device makes the serial clock active to start transmission, then transfers 1-byte data
in phase with the clock.
Fig. 8-12 Block Diagram of Synchronous Serial Interface
Internal bus
SI0
SO0/SB0
N-ch open-drain
output enabled
(when SB0 or
SBI mode is used)
SCK0
Direction
control circuit
SIO
Shift register
Set Clear
Output latch
Bus release/
command/
acknowledge
detection
circuit
Serial clock
counter
Serial clock
control circuit
Busy/
acknowledge
detection
circuit
Interrupt signal
generation
circuit
INTCSI
TM 3 output/2
fCLK/8
fCLK/32
Remark fCLK: Internal system clock frequency (system clock frequency/2)
40